1. Field of the Invention
The present invention relates generally to water soluble polymers, as well as to detergent compositions containing these polymers, the preparation of the polymers and detergent compositions, and use of the polymers. More specifically, this invention relates to copolymers of polymerizable ethylenically unsaturated C.sub.3 -C.sub.6 monocarboxylic acids and copolymerizable ethylenically unsaturated monomers including hydrophobic groups and polyalkyleneoxy groups, and to detergent compositions, especially heavy duty liquid detergent compositions for laundry and dishwashing use, and the use of the copolymers in these compositions.
2. Brief Summary of the Prior Art
The use of certain polycarboxylic acid compounds including polymeric polycarboxylic acid, and their salts, as additives in detergent compositions is known to enhance the efficiency of surfactants in wetting the substrate to be cleaned. These "sequestering builders" function by forming complexes with hard water ions, such as Calcium and magnesium, which otherwise inactivate anionic surfactants in the detergent composition. This insoluble material tends to deposit on fabric being washed, and interferes with the uptake of optical brighteners by the fabric from the wash water, resulting in dingy, unattractive fabric after washing. In addition to serving as a sequestering agent, a builder may also aid in keeping soil which has been removed by the washing process from redepositing on fabric being washed (antideposition agent) as well as to moderate the pH of the wash water (buffering agent). The multiple roles played by the builder during the cleaning process tend to make formulating a detergent Composition a difficult, trial-and-error process.
One type of polymeric polycarboxylic acid which is well known as a sequestering builder is hydrolyzed polymaleic anhydride. This type of builder is disclosed, for example, in U.S. Pat. Nos. 3,308,067, 3,557,005 and 3,676,373. Maleic anhydride copolymers and derivatives are also known in the art as detergent builders. For example, U.S. Pat. No. 3,794,605 discloses a built detergent composition including a mixture of water soluble salts of a cellulose sulfate ester and a copolymer of a vinyl compound and maleic anhydride. The builder enhances the "whiteness maintenance" of the detergent composition by preventing redeposition of soil and deposition of hardness ion builder salts on laundered fabrics. Water soluble salts of copolymers of a vinyl compound and maleic anhydride have also been used in detergent compositions. For example, U.S. Pat. No. 3,830,745 relates to water soluble salts of copolymers of maleic builder. Other maleic anhydride copolymers useful as builders include those prepared with styrene (U.S. Pat. No. 3,676,373), chloromaleic acid (U.S. Pat. No. 3,733,280), vinyl acetate or methyl methacrylate (U.S. Pat. No. 3,708,436), carbon monoxide (U.S. Pat. No. 3,761,412) tetrahydrophthalic anhydride (U.S. Pat. No. 3,838,113), as well as telomers with alkyl esters or alkylene carbonates (U.S. Pat. Nos. 3,758,419 and 3,775,475) and with vinyl alcohol (U.S. Pat. No. 3,793,228).
In a similar vein is U.S. Pat. No. 4,009,110 which discloses terpolymers of maleic anhydride, diketene, and vinyl alkyl ethers and their hydrolyzed derivatives as detergent builders and complexing agents, as well as the use of these terpolymers with the water soluble salts of higher molecular weight polycarboxylic acids, such as dicarboxylic acid polymers and copolymers with polymerizable monocarboxylic acids. U.S. Pat. No. 4,554,099 relating to an opaque general-purpose liquid cleaning composition discloses resin copolymers which are at least partially esterified with an alcohol, such as partially esterified adducts of rosin with maleic anhydride, and copolymers of maleic anhydride with vinyl methyl ether partially esterified with butanol. Streak-free liquid cleaners including similar copolymers are disclosed in U.S. Pat. No. 4,508,635. The use of partially hydrolyzed polymaleic anhydride as a component in a detergent composition adapted for washing textiles after they have been dyed is disclosed in U.S. Pat. No. 4,545,919.
U.S. Pat. No. 4,471,100 discloses copolymers of maleic acid salts and polyalkylene glycol monoallyl ether for use as dispersants in cements and mortars, inter alia. British patent specification No. 1,167,524 discloses similar copolymers, except that the polyalkyene glycol chain is capped by a monovalent aliphatic, cycloaliphatic, aryl aliphatic, aryl, alkylaryl, or acyl group, having at least four carbon atoms and that the polymerizable "surfactant monomer" can be derived from ethylenically unsaturated mono- or di- carboxylic acids as well as allyl-functional compounds.
Another invention in this tradition is that of U.S. Pat. No. 4,559,159 ("'159 patent"), which discloses copolymers of ethylenically unsaturated monocarboxylic and dicarboxylic acids (and their anhydrides, such as maleic anhydride) which are partially esterified with an alkoxylated (C.sub.1 -C.sub.18)alkyl phenol. These copolymers are used as "detergent assistants" to replace traditional detergent builders such as polycarboxylic acids. These assistants simultaneously optimize the primary and secondary detergent action of the detergent in the composition.
The use of maleic anhydride in the '159 patent appears to be motivated by the purported ease of preparation of maleic anhydride copolymers, in that these copolymers can be prepared by simply first copolymerizing the acid monomers in an aqueous solution and then partially esterifying the intermediate polymer by reaction of the alkoxylated alkyl phenol with maleic anhydride, thus forming the monoester (Col. 5, lines 54-64). In addition, a neutralization step can be avoided by using a mixture of the soluble salt of dicarboxylic acid and a monocarboxylic acid, or a mixture of the soluble salt of a monocarboxylic acid and the dicarboxylic acid (Col. 8, lines 53-65). The '159 patent notes an advance ove the art which employed maleic anhydride/acrylic acid copolymers and methyl vinyl ether/maleic anhydride copolymers (items 4 and 5 in the table in Col. 16).
Another general type of polymeric polycarboxylic acid builder is polyacrylic acid. U.S. Pat. No. 3,706,672, for example, discloses sodium polyacrylate as a substitute for polyphosphate builder in household detergent compositions. High chelation value polyacrylic acid is disclosed in U.S. Pat. No. 3,904,685. The use of oligomeric (molecular weight 500-10,000) poly(alkyl)acrylic acids and their salts as biodegradable builders for detergent compositions is disclosed in U.S. Pat. No. 3,922,230. Similarly. U.S. Pat. No. 3,950,260 relates to water soluble homopolymers of acrylic acid and methacrylic acid and their salts as builders, the preferred degree of polymerization being fixed by a viscosity criterion. Crosslinked homopolymers of acrylic acid are disclosed to be suitable "structuring agents" for highly alkaline liquid detergent compositions in U.S. Pat. No. 3,566,504.
Copolymers of acrylic acid and other monomers are also known as builders. For example, copolymers of acrolein and acrylic acid are disclosed as builders in U.S. Pat. Nos. 3,853,781 and 3,896,086. Similar polymers are disclosed in U.S. Pat. No. 4,031,022 which relates to copolymers of acrylic acid and alpha-hydroxyacrylic acid and their water soluble salts and use as detergent builders. These copolymers are capable of suspending lime (calcium carbonate) to an extent which significantly exceed their stoichiometric capacity. U.S. Pat. No. 3,920,570 describes a process for sequestering ions by employing a water soluble salt of a poly-alpha-hydroxyacrylic acid as a sequestering polyelectrolyte. Salts of terpolymers derived from alkyl alcohol, sulfur dioxide and acrylic or methacrylic acid are disclosed as replacements for phosphorous containing builders in U.S. Pat. No. 3,883,446. U.S. Pat. No. 3,719,647 discloses copolymers of (meth)acrylic acid and polyethoxylated (meth)acrylic acid as "whiteness maintenance" agents in conventional tripolyphosphate-built granular detergents. Preferably, these copolymers have a molecular weight between 30,000 and 200,000.
The use of mixtures of polyacrylic acid and other polymers in detergent compositions is also known. For example, the use of mixtures of polyacrylic acid and another polymer, poly(N,N-dicarboxymethacrylamide), as a builder is disclosed in U.S. Pat. No. 3,692,704. Similarly, the use of mixtures of polyethylene glycol and polyacrylate in detergent compositions is disclosed in U.S. Pat. No. 4,490,271 to improve the removal of clay soils. The mixture is preferably used at relatively low levels, and a non-phosphorous detergent builder must also be included in these solid detergent compositions.
U.S. Pat. No. 4,571,303 discloses the use of water soluble polyacrylates to improve the storage stability of soil release promoting copolymers of polyethylene terphthalate-polyoxyethylene terphthalate in particulate nonionic detergent compositions.
European patent application 84115433.9 published July 10, 1985 discloses copolymers of acrylamido alkane sulfonic acid and copolymerizable ethylenically unsaturated esters of hydrocarboxy poly(alkenoxy)alkanol with acrylic and methacrylic acids as lime soap dispersants.
Despite the substantial advances which have been made in the cleaning arts in reducing the amount of water-eutrofying phosphate builder in detergent compositions, and in reducing redeposition of soil and sequestering hard water ions (lime soap dispersancy) during the washing process by use of water soluble polyions, there remains a substantial need for further improvement, particularly in liquid cleaning compositions. The need is especially acute when detergent compositions are used in laundering all-cotton fabrics, which are particularly susceptible to soil redeposition during the cleaning process. Recently, clothing made with all cotton and other natural fabrics has become increasingly popular.
Modern liquid laundry detergents for home laundering are complex, highly-engineered products. See, for example, S. C. Stinson, Chemical and Engineerinq News, Jan. 26, 1987, pp. 21-46 and U.S. Pat. No. 4,507,219 (heavy duty liquid detergent composition containing eleven components). The formulation of liquid laundry detergent composition is a highly unpredictable process, given the complex variety of interactions possible among the multiple components of these products and the critical importance of surface phenomena in the cleaning process. There is a need for a product which can serve both as an antideposition agent in lime soap dispersants and which is not only compatible with the highly-complex liquid detergent compositions presently being marketed to the consumer, but which also functions without diminishing other important performance characteristics of the detergent compositions.